Fabric products, for example, sanitary products (such as underclothes, towels, handkerchiefs, and bedclothes), and garments (hereinafter, in the present specification, also simply referred to as “fabric products”) provide a comfortable sense of use and wear sensation when the fabric products are kept clean. Furthermore, fabric products such as garments are materials that are put on human bodies, and sanitary products such as towels and bedclothes are used by being brought into direct contact with human bodies. Therefore, it is important even from the viewpoint of hygiene to keep these fabric products clean. Along the enhanced recent social requirements for hygiene, the public interest in keeping these fabric products clean has increased.
In recent years, as consumers build up more interest in the living environment, it is desired more than ever to remove any unpleasant odors of personal belongings. The odors that cling to fabric products, for example, sanitary products and garments, include external factors such as cigarettes, as well as internal factors that are originated from human body, which are produced by repeated use of fabric products.
Since the above-described fabric products are brought into direct contact with human skin, the fabric products have a potential to absorb or attach sweat containing sebum, corneous substances and the like. For this reason, the fabric products may produce a characteristic malodor in a case where after laundry, laundered fabric products are left untouched in a damp place such as the inside of a laundering machine tub for a long time, in the case of having been dried indoors, in the case of having gotten wet with rain or sweat, or in the case of insufficiently dried fabric products. This malodor is generally called a damp-dry malodor, and this odor can be prevented from occurring by sufficiently drying the fabric products in some cases. However, even for fabric products which have been sufficiently dried and from which no damp-dry malodor is sensed, wet-and-dirty dustcloth-malodor-like damp-dry malodor may be produced when the fabric products become damp due to sweat, rain or the like. That is, if fabric products once produce this damp-dry malodor, the wet-and-dirty dustcloth-like damp-dry malodor is likely to recur at the time of use even when the damp-dry malodor can be temporarily eliminated by laundry. Such a damp-dry malodor that is prone to recur may be produced not only in a case where fabric products are dried indoors, but also in a case where a dryer or a washing machine having a low temperature drying function is used, and even in the case of fabric products that have been dried outdoors, if the fabric products become damp.
A feature of the recurrent damp-dry malodor lies in that the fabric product produces the malodor only by becoming damp. The recurrent damp-dry malodor is produced in some cases when fabric products are stored in a wardrobe or the like for a long time. Fabric products (such as underclothes, handkerchiefs or towels), which are frequently brought into contact with human skin and are used with a high use frequency and a short period of the wash-use cycle, are in many cases such that once this damp-dry malodor is produced, the malodor comes to recur during use. In order to inhibit this damp-dry malodor, it is important to treat fabric products so as not to produce such damp-dry malodor-causing substances. As a method for that purpose, there is a demand for a base material or a material which inhibits the damp-dry malodor. Also, there is a demand for the development of a method of evaluating inhibitory effect on damp-dry malodor for screening a damp-dry malodor inhibitor.
It has been hitherto reported that the damp-dry malodor is a complex odor composed of the “mold-like malodor” of medium-chain aldehydes, medium-chain alcohols, ketones and the like, the “sour malodor” of short-chain fatty acids, medium-chain fatty acids and the like, the “fishy malodor” of nitrogen compounds, and sulfur compounds (see Patent Literature 1). Patent Literature 1 also reports that the medium-chain fatty acids in particular have a high degree of contribution, and that a major component of the damp-dry malodor is speculated to be “a mixture of unsaturated fatty acids having a branched structure with 7 to 9 carbon atoms,” which are also contained in the foul odor of human sweat or the like. Further, as indicator substances for the damp-dry malodor, various kinds of fatty acids including 4-methyl-3-hexenoic acid have been hitherto suggested (see Patent Literature 1). The 4-methyl-3-hexenoic acid is naturally known as a component of citrons (see Non-Patent Literature 2), and it is also known that the 4-methyl-3-hexenoic acid is produced from terpenes by microorganisms (see Patent Literature 2). However, these literatures do not describe or suggest the mechanism of the production of the damp-dry malodor. Furthermore, there is no instance of devising a method of evaluating inhibitory effect on damp-dry malodor and a method of screening a damp-dry malodor inhibitor based on such a mechanism.